In determining the question of custody and guardianship, the paramount consideration is the welfare of the minor. The word `welfare' has to be taken in its widest sense, and must include the child's, moral as well as physical well-being, and also have regard to the ties of affection. The Hindu Minority and Guardianship Act, 1956 contains a provision which lays down that custody of a child upon the age of five should ordinarily be with the mother. Under other personal laws, though it is no such statutory provision, the Indian courts have consistently taken view. If divorce is inevitable, bitter battles cannot be the option to settle issues of child custody and access. Custody of a child, when parents divorce, only implies as to who the child will physically reside with. The non-negotiable principle on which custody is decided is the 'best interest and welfare of the child'. Who will best serve the child's emotional, educational, social and medical needs is the only criteria. The earning capacity of the parent does not determine custody but the capacity to provide a safe and secure environment does. Access to the non-custodial parent could be weekly, fortnightly, daily or monthly. It could be just day access or overnight access with gradual increase including weekend and/or vacation, access on special days, etc You can argue before court in the child custody case that his extra marital affair with another woman may not be a conducive situation for a better growth of your child and it may be detrimental to his future and career. All other aspects can be pleaded in the petition for custody in comparison with his own. If the child is still in your custody, you dont apply for custody, let him file a child custody case which you can strongly defend based on merits in your side.